Energy and nutrient cycling in pig production systems

Transcription

1 Graduate Theses and Dissertations Iowa State University Capstones, Theses and Dissertations 2009 Energy and nutrient cycling in pig production systems Peter J. Lammers Iowa State University Follow this and additional works at: Part of the Animal Sciences Commons Recommended Citation Lammers, Peter J., "Energy and nutrient cycling in pig production systems" (2009). Graduate Theses and Dissertations This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact

2 Energy and nutrient cycling in pig production systems by Peter J. Lammers A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Co-Majors: Animal Science; Sustainable Agriculture Program of Study Committee: Mark S. Honeyman, Co-major professor James B. Kliebenstein, Co-major professor Jay D. Harmon Michael D Kenealy Matthew J. Helmers Iowa State University Ames, Iowa 2009 Copyright Peter J. Lammers, All rights reserved.

3 ii TABLE OF CONTENTS CHAPTER 1. GENERAL INTRODUCTION 1 Dissertation organization 4 CHAPTER 2. LITERATURE REVIEW 5 Energy 5 Carbon 6 Life Cycle Assessment 7 LCA of Swine Feed Ingredients 8 Energy in Pig Nutrition 14 Amino Acids 17 References 19 Tables 23 CHAPTER 3. CONSTRUCTION RESOURCE USE OF TWO DIFFERENT TYPES AND SCALES OF IOWA SWINE PRODUCTION FACILITIES 25 Abstract 25 Introduction 26 Methods 27 Results 34 Conclusions 40 Acknowledgements 41 References 41 Tables 43 Figures 49 CHAPTER 4. ENERGY AND CARBON INVENTORY OF IOWA SWINE PRODUCTION FACILITIES 54 Abstract 54 Introduction 55 Methods 57 Results 77 Discussion 86 Acknowledgements 88 References 88 Tables 92 CHAPTER 5. DIGESTIBLE AND METABOLIZABLE ENERGY OF CRUDE GLYCEROL FOR GROWING PIGS 103 Abstract 103 Introduction 104 Materials and Methods 105

4 iii Results and Discussion 108 Acknowledgements 111 References 112 Tables 115 Figures 120 CHAPTER 6. GROWTH PERFORMANCE, CARCASS CHARACTERISTICS, MEAT QUALITY, AND TISSUE HISTOLOGY OF GROWING PIGS FED CRUDE GLYCERIN-SUPPLEMENTED DIETS 122 Abstract 122 Introduction 123 Materials and Methods 125 Results and Discussion 129 Acknowledgements 133 References 133 Tables 137 CHAPTER 7. NON-SOLAR ENERGY USE AND 100-YEAR GLOBAL WARMING POTENTIAL OF IOWA SWINE FEEDSTUFFS AND FEEDING STRATEGIES 145 Abstract 145 Introduction 146 Materials and Methods 148 Results and Discussion 154 Acknowledgements 162 References 162 Tables 166 CHAPTER 8. OPTIMIZING USE OF NON-SOLAR RESOURCES IN PIG PRODUTION: AN EXAMINATION OF IOWA SYSTEMS 174 Abstract 174 Introduction 175 Methods 177 Results 185 Acknowledgements 189 References 189 Tables 194 CHAPTER 9. GENERAL CONCLUSIONS 198 APPENDIX 1. CALCULATING ENERGY USE FOR THERMAL CONTROL OF GROW-FINISH FACILITIES WITHIN A FARROW-TO-FINISH SYSTEM PRODUCING

5 iv 15,600 MARKET PIGS ANNUALLY 203 References 209 Tables 211 APPENDIX 2. CROP PRODUCTION MODEL 216 Model Descriptions and Assumptions 216 Results 221 References 224 Tables 228 APPENDIX 3. PIG FEED INGREDIENT MANUFACTURING AND DELIVERY: PROCESS INVENTORY AND ASSUMPTIONS 234 Transportation and Diet Mixing 234 Primary Feed Ingredients 235 Bio-fuel Co-products 238 Micro-ingredients 241 Results 246 Conclusions 247 References 247 Tables 252 ACKNOWLEDGEMENTS 256

6 1 CHAPTER 1. GENERAL INTRODUCTION Life depends on three inter-woven basics: energy, nutrients, and a supporting environment. This dissertation is an examination of those three basics under the context of complementary crop and pig production in Iowa. The ultimate goal is to provide useful information to the general public, students, policy makers, and fellow academics about the potential impacts of different pig production systems. An overarching assumption of this dissertation is that pigs and crops will be raised in Iowa and that human society will not spontaneously alter its modus operandi. It is my hope that with information based decision making we can better address the mounting challenges we face and foster the advancement of a more sustainable agriculture. United States pig production is concentrated in Iowa, and is a major influence on the economic and ecological condition of that community. A pig production system includes buildings, equipment, feed ingredients, feed processing, and nutrient management at the individual farm level. Energy is used in all aspects of pig production, from the manufacture of materials used in building construction to the cultivation and processing of feedstuffs. Historically the availability of fossil fuels has minimized pressure to consider all uses of nonsolar energy in pig production. Rising energy prices, uncertain access to petroleum supplies, and recognition of the environmental impacts of using fossil fuels are increasing awareness and incentives to reduce the use of limited non-solar energy resources. Comprehensive, accurate information is critical to informed decision making. Analysis of non-solar energy

7 2 use by modern pig farms in the state of Iowa, the Midwest region, and the United States is lacking. Greenhouse gas emission by human activity impacts the supporting environment that all Earth-based life relies on. The emission of greenhouse gases by agriculture is impacted by both crop and livestock sectors. Consumption of energy results in emission of greenhouse gases. If non-solar energy use in the construction and operation of a pig farm can be minimized, greenhouse gas emissions may decline. Both carbon sequestration and soil erosion potential is heavily influenced by cropping systems and indirectly affected by diets fed to pigs. If a perennial crop such as alfalfa could be incorporated into the feeding regime of pigs, there may be potential for decreasing losses of soil and soil bound nutrients due to erosion and generation of soil organic matter through carbon sequestration. Nutrient cycling within an agricultural system can greatly impact energy use by that system. Internal cycling of nutrients such as occurs when pig manure is returned to fields producing the crops that ultimately feed the growing pigs may lower the need for synthetic sources of fertility. Synthetic forms of fertility typically require significant amounts of energy to generate and transport. Thus utilizing locally produced, animal-based sources of fertility can lower the non-solar energy use of crop production. Nutrients can also move from a pig production system to air and water and thus impact the supporting environment. Energy use, nutrient cycling, and ecological impacts on the global environment of agricultural systems are not isolated events or entities. Rather they are interconnected influences which must be considered simultaneously when evaluating the desirability of a given production system, or when designing an agroecosystem suitable for a particular landscape. Models are simplified representations of complex reality and as such allow

8 3 modelers to predict likely trends within a system as well as the magnitude of changes resulting from management decisions. The utility of a model obviously relies to a great extent on the accuracy of modeling assumptions used as well as correctly representing the relationships and interactions that occur within a system. Although imperfect, models can be powerful analytical tools. Thus to predict the comparative non-solar energy use and ecological impacts of different pig production systems a series of complimentary and interconnected models were developed and used. This dissertation quantifies non-solar energy use in the construction and operation of pig production systems in Iowa. A pig production system includes buildings, equipment, feed ingredients, feed processing, and nutrient management at the individual farm level. Non-solar energy use, nutrient cycling, and environmental impact by different phases of pig production, under different diet and facility scenarios are modeled and compared using process analysis methodology. All energy inputs (direct and indirect) into a pig production system are considered based upon physical material flows. Direct energy is used within the system for agricultural production. Diesel fuel, electricity, and feed use are examples of direct energy. Energy used to produce farm inputs such as mineral fertilizers, seeds, gates, building materials and equipment are examples of indirect or embedded energy. For this project, indirect energy use one-step backwards from the farm is considered e.g. the energy used to produce gates and feeders will be included but not the energy used to manufacture the equipment to produce the gates and feeders. Energy and material flows within and out of a pig production system are compared to energy and material flows into the system in order to calculate energy use efficiency.

9 4 DISSERTATION ORGANIZATION This thesis is divided into a literature review, six papers, a general summary, and three appendices. The six manuscripts that comprise the bulk of this dissertation have been published, accepted for publication, or are awaiting submission to an appropriate scientific journal and are individually formatted according to the guidelines of each journal.

10 5 CHAPTER 2: LITERATURE REVIEW ENERGY There are two broad categories of energy embodied and operating. Embodied energy is the energy required to produce, manufacture, provide, or supply a product, material, or service (Hammond and Jones, 2008b). In pig buildings, energy used to manufacture facility components such as concrete, steel, and plastics are examples of embodied energy. Operating energy is the energy directly used by a system to function on a daily basis. In pig buildings, electricity to operate ventilation systems, liquefied petroleum gas to heat buildings, and diets fed to pigs are examples of operating energy. To borrow terminology from economics, operating energy can be considered analogous to variable costs costs (energy use) that are incurred only if pig production occurs. Alternatively, embodied energy can be viewed as fixed costs costs (energy use) that are incurred to create and maintain the means of production even if no pigs are actually raised. GREENHOUSE GASES The emission of energy related pollutants is a major influence of global climate alteration (IPCC, 2006, 2007). Global climate altering emissions (greenhouse gases) are usually reported in terms of carbon equivalents (IPCC, 2006, 2007). Three greenhouse gases are of primary importance when relating global climate change to energy use carbon dioxide (CO 2 ), methane (CH 4 ) and nitrous oxide (N 2 O) (IPCC, 2006, 2007). Global warming potential (GWP) is a measure of how much a given mass of greenhouse gas contributes to global climate change (IPCC, 2006, 2007). Global warming potential is calculated over a period of time and so a time-scale must be reported in order for GWP s of different processes to be meaningfully compared. Reporting greenhouse gas emissions in terms of 100-year

11 6 GWP relative to CO 2 is standard international practice (IPCC, 2007). Table 1 presents 100-yr GWP of the three greenhouse gases of primary interest. As table 1 shows, all greenhouse gases are not equal. For example 1.0 kg N 2 O has the 100-yr GWP of kg CO 2. Caculating 100-yr GWP from energy consumption is simply a matter of converting emissions of CO 2, CH 4, and N 2 O into CO 2 equivalents and summing the results. Combusting 1 GJ of liquefied petroleum gas (LP gas) on farms is reported to result in emission of 63,100 g CO 2, 5.0 g CH 4, and 0.1 g N 2 O per GJ of energy released (IPCC, 2006). Equation 1 presents the calculation of the 100-yr GWP of burning 1 GJ LP gas. Equation 1 63,100 g CO 2 1 GJ LP gas 1 g CO 2 equivalents 63,100 g CO 2 equivalents 1 g CO 1 GJ LP gas g CH4 1 GJ LP gas 25 g CO 2 equivalents 125 g CO 2 equivalents 1 g CH 1 GJ LP gas g N2O 1 GJ LP gas 298 g CO 2 equivalents 29.8 g CO2 equivalents 1 g N O 1 GJ LP gas 2 63,100 g 125 g 298 g 63,523 g CO 2 equivalents 1 GJ LP gas The energy density assumptions and calculated 100-yr global warming potential of six sources of energy on Iowa farms is summarized as table 2. CARBON Linking greenhouse emissions with energy consumption gives rise to the notion of embodied carbon (Hammond and Jones, 2008b) and operating carbon. For example the embodied carbon of steel used in a pig building would be the greenhouse gas emissions associated with consumption of energy during production of that steel. Similarly, the

12 7 operating carbon of a ventilation system in a pig barn would be the greenhouse gas emissions that result from generation of electricity to operate fans. LIFE CYCLE ASSESSMENT Life cycle assessment (LCA) is a technique to analyze the environmental aspects and impacts associated with a product, process or service (ISO, 2006; EPA, 2008b). The main components of LCA include: 1) Inventory of all relevant energy and material inputs and environmental releases 2) Evaluation of the impacts associated with inputs and releases (ISO, 2006; EPA, 2008b) As the name implies LCA examines the life span of a product or service. This allows more complete accounting of the environmental impact of goods and services, but also necessitates clearly defining the beginning and end points of a product s lifespan. There are several approaches to LCA ranging from cradle-to-gate, cradle-to-grave, and cradle-to-cradle (Hawken et al., 1999; Hammond and Jones, 2008a; Hammond and Jones, 2008b). The main difference is in the endpoint of the examined life cycle. For clarity, consider the basic example of a steel pig feeder. Cradle-to-grave LCA begins with extraction of raw materials (including recycled materials if applicable) needed to produce a product and ends with disposal of the product at the end of its use (Hammond and Jones, 2008a). Using our steel feeder example, the cycle begins with mining of iron ore and ends with eventual scrapping of the feeder after several years of use. Cradle-to-cradle LCA begins with extraction of raw materials (including recycled materials if applicable) needed to produce a product and ends with the recycling of the product into another product (Hawken et al., 1999). In this case the LCA would end with the recycling of the steel feeder into another

13 8 metal product. Cradle-to-gate LCA begins with extraction of raw materials (including recycled materials if applicable) and ends with delivery of the product to its point of use. In this case the LCA would end when the feeder is delivered to a pig farm (Hammond and Jones, 2008a; Hammond and Jones, 2008b). Because of the inherent difficulties in tracking inputs and impacts after a product has been delivered to its point of use, many LCA reports are technically cradle-to-gate analyses (LaHore and Croke, 1978; Ericksson et al., 2005; Dalgaard et al., 2008; Hammond and Jones, 2008b). LCA OF SWINE FEED INGREDIENTS Because feed is the largest single input in swine production, the energy inputs and associated environmental impacts of swine feed ingredients have received the most attention (LaHore and Croke, 1978; Binder, 2003; Ericksson et al., 2005; Nielsen et al., 2006; Nielsen and Wenzel, 2006; Dalgaard et al., 2008). LaHore and Croke reported support energy needed to produce 19 feed ingredients for Australian pig production (LaHore and Croke, 1978). This report excludes corn and does not provide nutritional analysis of the included ingredients (LaHore and Croke, 1978). Exogenous phytase and synthetic amino acids are an important part of consideration in modern pig production and providing those products is a multi-billion dollar business for ingredient manufacturers (Binder, 2003; Nielsen et al., 2006; Nielsen and Wenzel, 2006). Assessments of exogenous phytase have reported that the key energetic advantage of feeding phytase is reducing the amount of inorganic phosphorus in pig diets (Nielsen et al., 2006; Nielsen and Wenzel, 2006). From a pig production standpoint, it has been demonstrated that inclusion of exogenous phytase enables utilization of plant source phosphorus by pigs and allows diets containing reduced amounts of inorganic phosphorus to be nutritionally adequate

14 9 (Veum et al., 2006; Veum and Ellersieck, 2008; Emiola et al., 2009). Literature on the LCA of synthetic amino acids is less available. After an extensive search of multiple data bases, published articles, and personal communications with ingredient manufactures, only one publication presenting the production energy of synthetic amino acids could be found (Binder, 2003). Binder (2003) reports that chemical synthesis of 1.0 kg DL-methionine requires 88.0 MJ of primary energy. This value is considerably higher than the estimate of 50.0 MJ/kg for supplemental ingredients including synthetic amino acids reported by LaHore and Croke (1978). The paucity of information in the published literature pertaining to the energy required to produce L-lysine, the synthetic amino acid most commonly fed to pigs is unfortunate and should be rectified. Production of soybean meal in Argentina with subsequent delivery to Rotterdam Habor, in the Netherlands has been reported (Dalgaard et al., 2008). Imported soybean meal is a major source of amino acids for pigs in Europe (Ericksson et al., 2005; Dalgaard et al., 2008). The application of information presented by Dalgaard et al. (2008) to Iowa swine production must take into account the likelihood of substantial reductions in transportation energy required. Dalgaard et al. (2008) estimate an ocean voyage of more than 12,000 km for soybean meal from Argentina to the Netherlands. Given Iowa s leadership in U. S. soybean production (USDA, 2009) and processing (Hardy, 2009), it is reasonable to assume that soybean meal fed in Iowa travels a much shorter distance. ASSESSMENT OF PIG PRODUCTION INPUTS AND IMPACTS Iowa pig production in 1975 was estimated to require input of 2,622 MJ non-solar energy per 100 kg of liveweight (Reid et al., 1980). Approximately 65% of the energy input was directly associated with swine feed (Reid et al., 1980). For every 100 kg of pigs

15 10 produced 809 m 2 of cropland was required (Reid et al., 1980). United States pig production has changed dramatically since 1975, but Reid et al (1980) provides a historic perspective of Iowa pig production. The efficiency of Swedish pork production reportedly increased by approximately 20% between the years 1972 and 1993 (Uhlin, 1998). Feed and fertilizers accounted for 60% of the energy input in Swedish pork production in 1993 (Uhlin, 1998). Uhlin (1998) reported the total energy use for pig production relative to energy output in pork. This is a unique reporting strategy among the LCA literature pertaining to pig production. The researchers reported that in 1993, Swedish pork required 4.10 MJ non-solar energy input for every 1.0 MJ of pork produced (Uhlin, 1998). The energy density of fresh pork carcass, excluding bone and skin is reported as MJ/kg (USDA, 2008). Assuming a reported dressing percentage of 72% for pigs (Lammers et al., 2008), the non-solar energy input is calculated to be 46.4 MJ/kg live weight. Indicators of resource use and environmental impact for 5 pig farms in Denmark were collected for 3 years ( ) (Halberg, 1999). The selected farms did not statistically represent Danish farms, but they were typical pig farms for Denmark at that time (Halberg, 1999). Non-solar energy inputs of MJ per 1.0 kg of live weight was reported with no examination of the portion of non-solar energy committed to feed production presented (Halberg, 1999). Dutch researchers compared pork with pea-based protein for human nutrition and assumed 3,783 MJ of non-solar energy input for every kg pig (Zhu and van Ierland, 2004). The researchers included energy use for growing crops, manufacturing feed, pig farming, harvest of the animal, and processing of meat products (Zhu and van Ierland, 2004).

16 11 Although their precise methodology is opaque, it is estimated that Zhu and van Ierland (2004) attributed 70% of the total non-solar energy input to producing the pig or 2,650 MJ per kg live pig. A total of kg of CO 2 equivalents were attributed to each pig through the entire pork chain (Zhu and van Ierland, 2004). Because greenhouse gas emissions are closely tied to energy consumption, it is estimated that 70% of the total CO 2 equivalents (519 kg) were allocated to producing the kg market pig. The estimated non-solar energy use for pig production under different production schemes in France ranges from MJ per kg of pig (Basset-Mens and van der Werf, 2005). The scenario most closely resembling commodity pork production in the United States required 15.9 MJ of non-solar energy input and resulted in emission of 2.3 kg CO 2 equivalents per 1.0 kg of pig live weight (Basset-Mens and van der Werf, 2005). The French researchers estimated 2.7% of total non-solar energy use should be attributed to operation of pig housing with 74% of the non-solar energy use being associated with crop and feed production (Basset-Mens and van der Werf, 2005). Researchers in Sweden focused on the impact of feed choice on energy use and environmental impacts of pork production (Ericksson et al., 2005). Three scenarios for protein supply were considered imported soybean meal, locally produced peas and rapeseed cake, and locally produced peas and rapeseed cake with synthetic amino acids (Ericksson et al., 2005). Their analysis assumed soybean meal was imported from South America, this resulted in the pigs fed soybean meal based diets requiring 6.8 MJ non-solar energy input/kg pig growth (Ericksson et al., 2005). Pigs fed locally sourced peas and rapeseed cake required the least non-energy input, 5.3 MJ/kg growth (Ericksson et al., 2005). Adding synthetic amino acids to locally sourced peas and rapeseed cake dramatically reduced

17 12 predicted nitrogen excretion by the growing pigs, but resulted in use of 6.3 MJ non-solar energy per kg of pig growth (Ericksson et al., 2005). The researchers focused exclusively on the grow-finish stage of production and did not include energy use or environmental impacts resulting from operation of pig housing (Ericksson et al., 2005). The three dietary scenarios resulted in emission of 1.5, 1.3, and 1.4 kg CO 2 equivalents/kg of pig growth (Ericksson et al., 2005). A 2006 United Kingdom report estimated the non-solar energy use for 1.0 kg of pork as 17.0 MJ and the 100-yr GWP as 6.4 kg CO2 equivalents (Williams et al., 2006). The purpose of this report was to compare many different commodities with each other rather than methods for producing one particular product (Williams et al., 2006). Energy use for building operation was not reported and no comparisons of different types of pig farms were made (Williams et al., 2006). Belgium researchers used a Flemish farm database of technical and economic records to establish a representative specialized pig farm for modeling purposes (Meul et al., 2007). They used this model farm to estimate energy use efficiency for different farm types using process analysis methodology (Meul et al., 2007). This method calculates direct and indirect energy inputs based on physical material flows and ignores solar energy and human labor inputs (Jones, 1989). Although inclusion of human labor inputs would result in a more complete evaluation of agricultural systems the difficulty in quantifying and allocating human labor and the corresponding introduction of error into the analysis is generally considered to outweigh the potential benefits (Jones, 1989). Meul et al. (2007) considered energy input using the cradle-to-gate approach of LCA. They included embodied energy use one step backwards from the farm i.e. energy used to produce fertilizers was included,

18 13 energy used to manufacture the fertilizer plant was not (Meul et al., 2007). Non-solar energy use of 17.2 MJ/kg carcass weight was reported for the average pig farm model with 70% of the non-solar energy use being directly attributed to feed production (Meul et al., 2007). The researchers also generated a model representing the 5% most energy efficient pig farms and examined energy use for those operations (Meul et al., 2007). It is estimated that the most energy efficient pig farms require10.6 MJ of non-solar energy use/kg carcass weight with 73% of non-solar energy use directly attributed to feed (Meul et al., 2007). The most recent assessment of swine production was conducted in Denmark and focuses exclusively on global warming, eutrophication, acidification, and photochemical smog (Dalgaard et al., 2007). Resource use for grain, soybean meal, heat, and electricity are stated and can be used to calculate non-solar energy consumption. If a barley-soybean meal diet is assumed total non-solar energy inputs are MJ/kg pork (Dalgaard et al., 2007). This assumes a gross energy (GE) value for barley and soybean meal of 15.9 and 17.2 MJ/kg respectively (Sauvant et al., 2004). Valuing feed inputs based on GE is problematic from a nutritional standpoint, but is the most straightforward method to derive a non-solar energy input estimate from the provided information. For every 1.0 kg pork produced under the conditions of the Danish model, emission of 3.6 kg CO 2 equivalents occurs (Sauvant et al., 2004). Table 3 summarizes nine reports of energy use and CO 2 emissions for pork production. Recent work in this area has focused in Europe and Denmark in particular. There are fundamental differences between European and United State pigs production that limits the application of European results to inform decision making by pig producers in Iowa. European swine diets typically include more variety in feed ingredients and often include

19 14 high amounts of small grains such as barley. Peas, rapeseed cake, and soybean meal are all commonly used as protein sources in European swine diets. Iowa swine diets are almost entirely comprised of corn and soybean meal. Pigs are generally limit fed in Europe and fed ad libitum Iowa. Diet form may also vary. Feeding pelleted or liquid feeds in Europe is common while in the United States almost all diets are fed as dry mash. Some Iowa farms do provide water at the feeder, encouraging consumption of a wet-dry feed, but this strategy is very different from liquid feeding systems seen in Europe. Market weight in the United States is also heavier than in Europe. Finally climate conditions and primary environmental concerns are different between Europe and Iowa. ENERGY IN PIG NUTRITION Approximately 60-80% of the total cost of pork production can be attributed to providing feed to the animal (Fowler, 2007). And energy components account for 80-90% of pig diets by mass (Holden et al., 1996). Historically highly digestible starches have been the primary source of energy in pig diets with fats and oils playing an important role particularly in diets for young pigs. Forages and nonstarch polysaccharides are of limited use in modern growing pig diets although these feedstuffs can be fed to pregnant sows without negative effects on reproductive performance (Calvert et al., 1985; van der Peet-Schwering et al., 2002). Proteins can be catabolized by the pig. Proteins are less energy dense than lipids and have an energy density that is similar to carbohydrates (Berg et al., 2002; Salway, 2004). Catabolism of proteins requires elimination of nitrogen from the body, an activity that lowers the net gain in biologically useful energy from oxidation of proteins relative to carbohydrates and lipids (Berg et al., 2002; Salway, 2004). Traditionally the price premium paid for

20 15 proteinaceous feedstuffs has been too high for widespread use of protein as a source of energy for pigs. Gross energy (GE) is the theoretical maximum energy that could be used by the pigs and is defined as the energy releases as heat following total combustion of a feedstuff (NRC, 1998; Ewan, 2001). Although GE is the starting point for further calculations, it is not a good measure of useful energy for pigs because it does not consider any of the losses of energy during ingestion, digestion, and metabolism of a feedstuff (Moehn et al., 2005). For example 1.0 kg of starch has approximately the same amount of GE as 1.0 kg of straw (Moehn et al., 2005) and 1.0 kg of corn has similar GE as 1.0 kg of soybean hulls (Sauvant et al., 2004). Terms commonly used to describe dietary energy include DE, ME, and NE (Ewan, 2001; Moehn et al., 2005). Digestible energy (DE) is the GE of the feed consumed minus the GE of the feces excreted (NRC, 1998; Ewan, 2001; Moehn et al., 2005). Metabolizable energy (ME) is DE minus energy excreted in urine and combustible gases (NRC, 1998; Ewan, 2001; Moehn et al., 2005). While DE and ME are relatively simple to determine, they only express potential energy and do not take into consideration the pig s ability to utilize energy from different dietary sources (Moehn et al., 2005; Noblet, 2006, 2007). Given work demonstrating pigs utilize energy present in consumed starch, protein, and lipid at different efficiencies (van Milgen et al., 2001), DE and ME values for feedstuffs are limited. The practical effect of using DE and ME systems is that they typically overestimate the energy value of protein and underestimate the energy value of lipids (Noblet, 2007; Payne and Zijlstra, 2007). Net energy (NE) values of feedstuffs provide a more precise measure of the energy available for use by the animal (Ewan, 2001; Moehn et al., 2005; Noblet, 2007). Net energy

21 16 is defined as ME minus the heat produced during digestion of feed, metabolism of nutrients, and excretion of wastes (Ewan, 2001; Moehn et al., 2005). The energy left following those losses energy in feces, urine, and gaseous products of digestion, and heat produced during digestion, metabolism, and excretion is the energy actually used by the animal for maintenance and production (Moehn et al., 2005; Noblet, 2006, 2007). Net energy is thus the only system that expresses usable dietary energy by incorporating the efficiency of nutrient use. Most North American swine nutritionists are most familiar with DE and ME systems. Although DE or ME systems may have been sufficient when formulating simple diets containing primarily corn and soybean meal, the advantages of the NE system are greater as diet complexity increases. Discussion surrounding adoption and application of a net energy system is on-going among North American swine nutritionists (Moehn et al., 2005 ; Payne and Zijlstra, 2007; Zijlstra and Payne, 2008). As noted by Payne and Zijlstra (2007) the efficacy of any energy system is dependent upon the accuracy of the energy values assigned to a set of ingredients. The DE, ME, and NE values of many ingredients can be readily obtained from feeding tables (NRC, 1998; Sauvant et al., 2004) but use of those values are only appropriate for ingredients having chemical characteristics similar to those in the tables (Noblet, 2007). As feed ingredients become increasingly differentiated DDGS from one particular ethanol plant, soybean meal from low linolenic acid soybeans, low phytate corn the task of updating ingredient nutrient matrices to reflect the feed ingredient actually used becomes critical. Payne and Zijlstra (2007) provide an action plan for analyzing ingredients, calculating values, and adjusting formulation schemes accordingly. Equations for calculating NE from chemical analysis of crude protein, fat, and fiber; moisture; ash; acid and neutral detergent fiber; sugar; and starch

22 17 were proposed by Noblet et al. (1994). These equations are the basis for the energy values reported by Sauvant et a. (2004). The most recent NRC for swine presents NE values based on the work of several different researchers (NRC, 1998) and in general NE values reported by NRC are lower than those explicitly calculated by Sauvant et al. (2004). AMINO ACIDS Growing pigs fed grain-based diets typical of modern swine production eat to satisfy a demand for energy and so the quantity of feed consumed depends on the energy density of the diet fed (NRC, 1998; Ellis and Augspurger, 2001; Ewan, 2001; Whittemore et al., 2003). Nutrient-to-energy ratios are thus important considerations when formulating and comparing pig diets (NRC, 1998; Ellis and Augspurger, 2001; Ewan, 2001; Whittemore et al., 2003). It is well established that different amino acids are required in different proportions to support growth of pigs (Lewis, 2001) and current nutrient recommendations relate intake of the essential amino acids in proportion to intake of lysine (NRC, 1998; Whittemore et al., 2003). The amino acid present in the least amount relative to the pig s requirement is known as the first limiting amino acid (Lewis, 2001; Whittemore, 2006). Lysine is generally the first limiting amino acid in practical swine diets with methionine, threonine, and tryptophan also being of key concern (Lewis, 2001). SWINE NUTRITION RECOMMENDATIONS Nutrition recommendations for swine in the United States are currently based on metabolizable energy and apparent ileal digestible amino acids (NRC, 1998). A net energy (NE) system considers the amount of heat lost during digestion and subsequent deposition of nutrients in body tissue and is thus a more accurate estimate of the true energy content of an ingredient (Ewan, 2001; Moehn et al., 2005; Noblet, 2007). Discussion of the practicality and

23 18 application of a net energy system is on-going among North American swine nutritionists (Moehn et al., 2005 ; Payne and Zijlstra, 2007; Zijlstra and Payne, 2008). At present standardized ileal digestibility is the most accurate basis for diet formulations in regards to amino acids availability (Gabert et al., 2001; Sauvant et al., 2004; Stein et al., 2007a; Stein et al., 2007b). More recent European recommendations are based on net energy and standardized ileal digestible amino acids (Whittemore et al., 2003). Feedstuff tables presenting the NE and SID amino acid content of feed ingredients are available (Whittemore et al., 2003; Sauvant et al., 2004). REFERENCES Basset-Mens, C., and H. M. G. van der Werf Scenario-based environmental assessment of farming systems: The case of pig production in France. Agriculture Ecosystems and Environment 105: Berg, J. M., T. L. Tymoczko, and L. Stryer Biochemistry. 5th ed. W. H. Freeman and Company, New York, NY. Binder Life cycle analysis of DL-Methionine in broiler meat production. Amino News. Evonik Degussa GmbH, Available online: Accessed: March 7, Calvert, C. C., N. C. Steele, and R. W. Rosebrough Digestibility of fiber components and reproductive performance of sows fed high levels of alfalfa meal. Journal of Animal Science 61: Dalgaard, R., N. Halberg, and J. E. Hermansen Danish pork production: An environmental assessment. DJF Animal Science 82: Dalgaard, R., J. Schmidt, N. Halsberg, P. Christensen, M. Thrane, and W. A. Pengue LCA of soybean meal. International Journal of Life Cycle Assessment 13: Downs, H. W., and R. W. Hansen Estimating farm fuel requirements. No Colorado State University Extension, Fort Collins, CO. Available online: Accessed: February 2, 2009.

24 19 Ellis, M., and N. Augspurger Chapter 20: Feed intake in growing-finishing pigs. In: A. J. Lewis and L. L. Southern (eds.) Swine nutrition. p CRC Press, Boca Raton, FL. Emiola, A., O. Akinremi, B. Slominski, and C. M. Nyachoti Nutrient utilization and manure P excretion in growing pigs fed corn-barley-soybean based diets supplemented with microbial phytase. Animal Science Journal 80: EPA. 2008a. egrid subregion GHG output emission rates for year Washington, D. C. Available online: Accessed: January 23, EPA. 2008b. Life cycle assessment. Washington D. C. Available online: Accessed: March 23, Ericksson, I. S., H. Elmquist, S. Stern, and T. Nybrant Environmental systems analysis of pig production: The impact of feed choice. International Journal of Life Cycle Assessment 10: Ewan, R Chapter 5: Energy utilization in swine nutrition. In: A. J. Lewis and L. L. Southern (eds.) Swine nutrition. p CRC Press, Boca Raton, FL. Fowler, T pig cost of production in selected countries. British Pig Executive, Milton Keynes, UK. Gabert, V. M., H. Jorgense, and C. M. Nyachoti Chapter 9: Bioavailability of amino acids in feedstuffs for swine. In: A. J. Lewis and L. L. Southern (eds.) Swine nutrition. p CRC Press, Boca Raton, FL. Halberg, N Indicators of resource use and environmental impact for use in a decision aid for Danish livestock farms. Agriculture Ecosystems and Environment 76: Hammond, G., and C. Jones. 2008a. Inventory of carbon and energy. Version 1.6a. Department of Mechanical Engineering, University of Bath, Bath, UK. Available online: Accessed: February 2, Hammond, G. P., and C. I. Jones. 2008b. Embodied energy and carbon in construction materials. Proceedings of the Institution of Civil Engineers: Energy 161: Hardy, C Update on ethanol and soy processing in Iowa. Iowa State University Extension, Ames, IA. Available online: POWs/POW 180/2009/Hardy2.html. Accessed: March 24, Hawken, P., A. Lovins, and L. H. Lovins Natural capitalism. Little, Brown and Company, Boston, MA.

25 20 Hill, J., E. Nelson, D. Tilman, S. Polasky, and D. Tiffany Environmental, economic, and energetic costs and benefits of biodiesel and ethanol biofuels. Proceedings of the National Academy of Sciences 103: Holden, P., R. Ewan, M. Jurgens, T. Stahly, and D. Zimmerman Life cycle swine nutrition. PM-489. Iowa State University Extension, Ames, IA. Huo, H., M. Wang, C. Bloyd, and V. Putsche Life-cycle assessment of energy and greenhouse gas effects of soybean-derived biodiesel and renewable fuel. Argonne National Laboratory, Argonne, IL. Available online: Accessed: February 6, IPCC IPCC guidelines for national greenhouse gas inventories. Kamiyamaguchi, Japan. Available online: Accessed: January 14, IPCC Climate change 2007: The physical science basis. Intergovernmental Panel on Climate Change, Geneva, Switzerland. ISO Environmental management life cycle assessment requirements and guidelines. ISO 14044:2006. International Organization of Standardization, Switzerland. Jones, M. R Analysis of the use of energy in agriculture approaches and problems. Agricultural Systems 29: LaHore, R., and B. Croke Energetics of stockfeed production. Animal Feed Science and Technology 3: Lammers, P. J., B. J. Kerr, T. E. Weber, K. Bregendahl, S. M. Lonergan, K. J. Prusa, D. U. Ahn, W. C. Stoffregen, W. A. Dozier III, and M. S. Honeyman Growth performance, carcass characteristics, meat quality, and tissue histology of growing pigs fed crude glycerol-supplemented diets. Journal of Animal Science 82: Lewis, A. J Chapter 8: Amino acids in swine nutrition. In: A. J. Lewis and L. L. Southern (eds.) Swine nutrition. p CRC Press, Boca Raton, FL. Meul, M., F. Nevens, D. Reheul, and G. Hofman Energy use efficiency in specialised dairy, arable, and pig farms in Flanders. Agriculture, Ecosystems and Environment 119: Moehn, S., J. Atakora, and R. O. Ball Using net energy for diet formulation: Potential for the Canadian pig industry. Advances in Pork Production 16: Nielsen, P. H., K. M. Oxenbøll, and H. Wenzel Cradle-to-gate environmental assessment of enzyme products produced industrially in Denmark by Novozymes

26 21 A/S. International Journal of Life Cycle Assessment OnlineFirst (DOI:http//dx.doi.org/ /lca ). Nielsen, P. H., and H. Wenzel Environmental assessment of Ronozyme P5000 CT Phytase as an alternative to inorganic phosphate supplementation to pig feed used in intensive pig production. International Journal of Life Cycle Assessment OnlineFirst (DOI:http//dx.doi.org/ /lca ). Noblet, J Recent advances in energy evaluation of feeds for pigs. In: P. C. Garnsworthy and J. Wiseman (eds.) Recent advances in animal nutrition Nottingham University Press, Nottingham, UK. Noblet, J Recent developments in net energy research for swine. Advances in Pork Production 18: Noblet, J., H. Fortune, X. S. Shi, and S. Dubois Prediction of net energy value in swine feeds for growing pigs. Journal of Animal Science 72: NRC Nutrient requirements of swine. 10th rev. Ed. National Academy Press, Washington D. C. Payne, R. L., and R. T. Zijlstra A guide to application of net energy in swine feed formulation. Advances in Pork Production 18: Reid, J. T., P. A. Oltenacu, M. S. Allen, and O. D. White Cultural energy, land and labor requirements of swine production systems in the U.S. In: D. Pimentel (ed.) CRC handbook of energy utilization in agriculture. p CRC Press Inc., Boca Raton, FL. Salway, J. G Metabolism and a glance. 3rd ed. Blackwell Publishing, Ltd., Oxford, UK. Sauvant, D., J. M. Perez, and G. Tran (eds) Tables of composition and nutrition value of feed materials: Pigs, poultry, cattle, sheep, goats, rabbits, horses, fish. 2nd edition. Wageningen Academic Publishers Wageningen, NL. Stein, H. H., M. F. Fuller, P. J. Moughan, B. Sève, R. Mosenthin, A. J. M. Jansman, J. A. Fernández, and C. F. M. de Lange. 2007a. Definition of apparent, true, and standardized ileal digestibility of amino acids in pigs. Livestock Science 109: Stein, H. H., B. Sève, M. F. Fuller, P. J. Moughan, and C. F. M. de Lange. 2007b. Amino acid bioavailability and digestibility in pig feed ingredients: Terminology and application. Journal of Animal Science 85: Uhlin, H.-E Why energy productivity is increasing: An I-O Analysis of Swedish agriculture. Agricultural Systems 56:

27 22 USDA USDA national nutrient database for standard reference. Release 21. USDA- ARS, Washington D. C. Available online: Accessed: March 24, USDA Census of agriculture. USDA-National Agricultural Statistics Service, Washington D. C. Available online: Accessed: March 11, van der Peet-Schwering, C. M. C., B. Kemp, G. P. Binnendijk, L. A. d. Hartog, A. M. Spoolder, and M. W. A. Verstegen Performance of sows fed high levels of nonstarch polysaccharides during gestation and lactation over three parities. Journal of Animal Science 81: van Milgen, J., J. Noblet, and S. Dubois Energetic efficiency of starch, protein, and lipid utilization in growing pigs. Journal of Nutrition 131: Veum, T. L., D. W. Bollinger, C. E. Buff, and M. R. Bedford A genetically engineered Escherichia coli phytase improves nutrient utilization, growth performance, and bone strength of young swine fed diets deficient in available phosphorus. Journal of Animal Science 84: Veum, T. L., and M. R. Ellersieck Effect of low doses of Aspergillus niger phytase on growth performance, bone strength, and nutrient absorption and excretion by growing and finishing swine fed corn-soybean meal diets deficient in available phosphorus and calcium. Journal of Animal Science 86: Whittemore, C. T Chapter 11: Energy and protein requirements for maintenance, growth, and reproduction. In: I. Kyriazakis and C. T. Whittemore (eds.) Whittemore s science and practice of pig production, 3rd edition. p Blackwell Publishing, Oxford, UK. Whittemore, C. T., M. J. Hazledine, and W. H. Close Nutrient requirement standards for pigs. British Society of Animal Science, Penicuik, Scotland, UK. Williams, A. G., E. Audsley, and D. L. Sandars Determining the environmental burdens and resource use in the production of agricultural and horticultural commodities. Main Report. Defra Research Project ISO205. Cranfield University, Silsoe, UK. Zhu, X., and E. C. van Ierland Protein chains and environmental pressures: A comparison of pork and novel protein foods. Environmental Sciences 1: Zijlstra, R. T., and R. L. Payne Practical application of the net energy system in swine nutrition. Journal of Animal Science 86 E-Suppl. 2: 606.

28 23 Table 1. One hundred year global warming potential of three primary greenhouse gases a Common name Chemical Formula 100-yr GWP, CO 2 equivalents Carbon dioxide CO 2 1 Methane CH 4 25 Nitrous oxide N 2 O 298 a (IPCC, 2007) Table 2. Energy density and 100-yr global warming potential of common Iowa farm fuels Fuel Energy density, MJ/L 100-yr GWP, g CO 2 /MJ Corn grain 11.7 a na Liquefied petroleum gas b c Number 2 diesel b c Electricity na d Ethanol 21.3 e na Biodiesel 34.5 f na a Gross energy of corn grain is 16.2 MJ/kg (Sauvant et al., 2004) b (Downs and Hansen, 1998). c (IPCC, 2006). d Calculated from weighted average of fuels consumed for electricity generation and transmission losses for Iowa (IPCC, 2006; EPA, 2008a) e (Hill et al., 2006). f (Hill et al., 2006; Huo et al., 2008)

29 24 Table 3. Summary of published energy assessments of pig production a Non-solar energy input, MJ/kg live wt. Non-solar energy attributed to feed, % of total Emissions, kg CO 2 equivalents/ kg live wt. Production Location Year Iowa b nr United States b nr Sweden c nr Denmark d NR nr Belgium e nr Belgium f nr Denmark g NR 4.6 France h Denmark i Denmark j Denmark k United Kingdom l nr 8.8 Denmark m nr 5.0 a Assumes 1 kg of pork = 1.38 live weight b (Reid et al., 1980) c (Uhlin, 1998) d (Halberg, 1999) e Average farm examined (Meul et al., 2007). f Top 5% energy efficient pig farms in database (Meul et al., 2007). g (Zhu and van Ierland, 2004) h (Basset-Mens and van der Werf, 2005) i Imported soybean meal as protein source, finishing phase only (Ericksson et al., 2005). j Local pea and rapeseed meal as protein source, finishing phase only (Ericksson et al., 2005). k Local pea and rapesedd meal with synthetic amino acids, finishing phase only (Ericksson et al., 2005). l (Williams et al., 2006) m Calculated based on gross energy of barley-soybean meal diet (Dalgaard et al., 2007).

30 25 CHAPTER 3. CONSTRUCTION RESOURCE USE OF TWO DIFFERENT TYPES AND SCALES OF IOWA SWINE PRODUCTION FACILITIES A paper accepted by Applied Engineering in Agriculture P. J. Lammers, M. S. Honeyman, J. D. Harmon, J. B. Kliebenstein, and M. J. Helmers 1 ABSTRACT. As global populations and affluence rise, there is increasing demand for energy, animal protein, and construction materials. In many cases, available resource pools are insufficient to meet growing market demands, resulting in increased prices and competition for limited resources. This study evaluates key construction resources needed to build different types and scales of Iowa swine production facilities. Two types of facilities conventional confinement and hoop barn-based within farrow-to-finish pig production systems scaled to produce either 5,200 or 15,600 market pigs annually are examined. Conventional confinement facilities are typical of pork industry practice in the United States and are characterized by individual gestation stalls and 1,200 head grow-finish buildings with slatted concrete floors and liquid manure systems. The hoop barn-based alternative uses bedded group pens in hoop barns for gestation and finishing. Five building materials: concrete, steel, lumber, thermoplastics, insulation, as well as crushed rock and diesel fuel used for building site preparation are considered. Land surface area required for buildings 1 The authors are Peter J. Lammers, Research Assistant, Department of Animal Science, Mark S. Honeyman, Professor, Department of Animal Science, Jay D. Harmon, ASABE Member Engineer, Professor, Department of Agricultural and Biosystems Engineering, James B. Kliebenstein, Professor, Department of Economics, and Matt J. Helmers, ASABE Member Engineer, Assistant Professor, Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, Iowa. Corresponding author: Mark S. Honeyman, Department of Animal Science, 32 Curtiss Hall, Iowa State University, Ames, Iowa 50011; phone: , fax: ; honeyman@iastate.edu.

31 26 and pig production infrastructure are also compared. Relative market costs of newly constructed swine facilities are compared under several material price scenarios. Using hoop barns for grow-finish and gestation results in lower construction costs. Increasing the scale of pig production results in lower construction costs per pig space, however the construction costs per pig space for a 5,200 head hoop barn-based complex is less than the construction costs per pig space for a 15,600 head conventional confinement system. In terms of construction resource use and cost, hoop barns for swine are a viable alternative that are less dependent on the scale of production than conventional confinement facilities. Keywords. Building materials, Construction costs, Hoop barn, Swine production. INTRODUCTION Global population is projected to reach 9.2 billion people in 2050 and if realized will represent an increase of more than 360% over a 100 year time period (UN, 2007). Population in China and the United States is also projected to increase dramatically (UN, 2007). Those two countries lead the world in pork production and consumption, a trend that is likely to continue (den Hartog, 2005; FAO, 2006). Increased population and rising incomes have created increased market demand for energy, animal protein, and construction materials globally. Over time, increased market demand for available resources typically results in greater price competition for those resources. Thus it is appropriate to examine the relative efficacy of using construction resources to build different types and scales of animal protein production systems. This paper examines the material use for constructing different types and scales of Iowa swine production facilities. Relative costs of building different types and scales of Iowa swine production facilities are also compared under different pricing